In case there remained any doubt that the debate over immigration reform would be long and arduous, senators on Tuesday filed no less than 300 amendments to the bipartisan immigration bill crafted by the Gang of Eight.

Some of those amendments have only a tangential relationship to the core issue of immigration reform. Others are so politically toxic they could doom the full bill — which, for some lawmakers, is the whole point.

Indeed, opponents reportedly believe that slowing the legislation with a glut of proposed amendments could imperil its chances. "The longer this legislation is available for public review, the worse it's going to be perceived," Sen. Jeff Sessions (R-Ala.) recently toldThe New York Times. "The longer it lays out there, the worse it’s going to smell. The tide is going to turn."

Here, five of the most head-scratching, controversial amendments:

1. Beefing with South Korea's beef importsBack in 2003, South Korea imposed new restrictions on imports of U.S. beef over concerns about the spread of mad cow disease. The slight apparently continues to stick in the craw of Sen. Chuck Grassley (R-Iowa), who filed an amendment that would bar South Koreans from receiving E-5 visas — a special entrepreneurial visa — until the nation removes "age-based import restrictions" on U.S. beef.

2. Keeping undocumented workers in low-wage employmentOne amendment would make it legal for undocumented workers to hold jobs in the U.S. But while that would normally be music to the ears of reform supporters, the amendment isn't exactly an uplifting affirmation of the American dream.

3. Removing the "pathway to citizenship"The central aspect of the bipartisan immigration deal is the creation of a so-called pathway to citizenship for undocumented workers currently living in the United States. The bill's authors have insisted that such a provision must be part of a final immigration bill, with Sen. John McCain (R-Ariz.) saying recently, "There’s no way of getting this job done without giving people a path to citizenship."

"America is a nation of immigrants, built by immigrants and we need to honor that heritage by fixing our broken immigration system, while upholding the rule of law and championing legal immigration," Cruz said in a press release Tuesday.

4. Requiring DNA samples from prospective immigrantsIn addition to providing their basic background information, future immigrants to the U.S. would also have to submit a DNA sample for the government to keep on file.

At least that's what Sen. Orrin Hatch (R-Utah) is proposing. Under one of Hatch's amendments — he submitted 24 total — immigrants would be required to provide a DNA sample that would be checked against federal criminal databases.

"Inclusion of a DNA profile as part of any background check will ensure that decisions regarding residency status are made with fullest search of criminal activity and identification available," Hatch's office said in a statement.

The bill as written would ask immigrants for fingerprints and photos, but supporters say that a DNA database would be a massive encroachment on personal privacy.

5. Denying terrorists welfareThere was some concern among immigration reformers that a backlash over the Boston bombing suspects, both of whom came to the U.S. as immigrants, would hinder the bill's odds of passing. And indeed, one amendment proposed by Sessions would bar "terrorist aliens" from receiving government benefits. That's apparently a direct response to the revelation that Tamerlan and Dzhokhar Tsarnaev received welfare.

Sessions submitted 49 amendments, including provisions that would require all undocumented workers to be interviewed in person before being considered for legal status; declare that state and local immigration laws trump those at the federal level; and deny legal status to undocumented workers unless they can prove income at four times the poverty level for 10 years straight — which, as the Huffington Post's Elise Foley notes, would mean $46,000 per year for an individual.